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Photo Forum / Digital Photography / DSLR Cameras / July 2005Plastic vs metal lens mount
I've noticed that some manufacturers are using a plastic lens mount on DSLR lenses. I realize this isn't a "normal" plastic, but how long can something like this be expected to hold up and last? Obviously, if you never swap lenses it will last forever. Sheldon > I've noticed that some manufacturers are using a plastic lens mount on > DSLR > lenses. I realize this isn't a "normal" plastic, but how long can > something like this be expected to hold up and last? It won't..  SignatureStacey >I've noticed that some manufacturers are using a plastic lens mount on DSLR >lenses. I realize this isn't a "normal" plastic, but how long can something [quoted text clipped - 3 lines] > >Sheldon Plastic is GARBAGE in certain situations and since it is almost always used to cut costs, you KNOW it won't hold up like metal. There are composites that have some stability and rigidity, but they cost more than aluminum or s/s so you'll never see them in an average camera. I remember years ago when a cheap SLR (Canon T70?) used a crappy aluminum lens mount instead of chrome-plated brass and everyone complained about it's wear problems. In addition, plastic has other ugly characteristics that make it second-rate as well, such as too much thermal expansion and contraction. Also, unless it's machined, it generally does not have the precision of metal since all plastics change shape slightly when cast, blow molded, etc. Check out Ford's recent $750m problem with plastic V8 intake manifolds. Plastic is trash, it's cheap and easy to make and form, so it makes up the bulk of inexpensive consumer cameras. The next horror made of plastic will be molded aspheric lens components in lower-grade DSLR lenses. Why? Because it costs pennies to mold an acrylic lens versus up to hundreds of dollars to grind an asphere in glass. Since the camera makers don't really work to make lenses that accurate, and love to cut costs, it must make them angry that they can't find plastics of suitable refractive index to replace all-glass lenses. -Rich [] > The next horror made of plastic will be molded aspheric lens > components in lower-grade DSLR lenses. Why? Because it costs pennies [quoted text clipped - 3 lines] > that they can't find plastics of suitable refractive index to replace > all-glass lenses. My glasses have plastic lenses (I think) which appear to be hard-wearing, and very light considering the high refractive index. OK, they are not aspheric, but why should I be worried about such materials inside an optical system? David > [] >> The next horror made of plastic will be molded aspheric lens >> components in lower-grade DSLR lenses. Nikon have been doing this since 1991, with the 28-70mm zoom. According to the Nikon Compendium, way back in 1968 the 10mm f/5.6 OP had a plastic element. I don't think it's such a wicked thing to do. Andrew. > David J Taylor > <david-taylor@blueyonder.co.not-this-bit.nor-this-part.uk.invalid> [quoted text clipped - 10 lines] > > Andrew. Andrew, could you please be more careful in your quoting? It was RichA who made the "horror" comment, not me. I'm glad to hear that Nikon may indeed be ahead of the rest in using the most appropriate optical components for the job. Thanks, David >> [] >>> The next horror made of plastic will be molded aspheric lens [quoted text clipped - 7 lines] > >Andrew. As a basic subsitute for crown glass, acrylic plastic is somewhat acceptable if the elements don't have much curvature on them. They've been used in things like home theatre projector guns where a 5" wide aspheric would be prohibitively expensive. On Mon, 04 Jul 2005 08:01:53 GMT, "David J Taylor" <david-taylor@blueyonder.co.not-this-bit.nor-this-part.uk.invalid> wrote: >[] >> The next horror made of plastic will be molded aspheric lens [quoted text clipped - 11 lines] > >David Glasses are probably the least demanding of all optical elements. They can be out of spec by a large margin and still work well. They are already experiencing the problem of lenses not living up to the capability of the sensors out there. Adding plastic lens elements to the mix won't help matters. All lenses will eventually have to incorporate ED elements (and the heavy flint components needed to match with them). Plastics don't help, especially if the lens has any kind of magnification factor (telephoto) which is where you need better optical correction. > [] >> The next horror made of plastic will be molded aspheric lens [quoted text clipped - 11 lines] > > David There are special optical grade plastics used in lenses that work just fine. They just aren't used in the mount to hold the lens on. I'll bet your glasses have metal hinges and screws. > "David J Taylor" > <david-taylor@blueyonder.co.not-this-bit.nor-this-part.uk.invalid> [quoted text clipped - 19 lines] > just fine. They just aren't used in the mount to hold the lens on. I'll > bet your glasses have metal hinges and screws. Indeed, yes. I wasn't querying the lens mount, but RichA's comment on the optics themselves. Cheers, David > Since the camera makers don't really work to make > lenses that accurate, and love to cut costs, it must make them angry > that they can't find plastics of suitable refractive index to replace > all-glass lenses. > -Rich Manufacturers of styrene-allyl alcohol co-polymer say "hi." >>I've noticed that some manufacturers are using a plastic lens mount on DSLR >>lenses. I realize this isn't a "normal" plastic, but how long can something [quoted text clipped - 20 lines] > > -Rich You are funny, if nothing else. Not only did I work for a (highly regarded) "plastics" manufacturing company, I currently work for a (highly regarded) Aerospace company. We are substituting metal with plastic more and more. I can assure you, if plastic was crap Boeing and Airbus would not be giving us approval to us it. To the OP: If the correct plastic is used, it could easily out last the camera itself. -- Slack > To the OP: If the correct plastic is used, it could easily out last the > camera itself. Sure - if it's a Canon which lasts only 12-28 months ... > I've noticed that some manufacturers are using a plastic lens mount on > DSLR lenses. I realize this isn't a "normal" plastic, but how long [quoted text clipped - 3 lines] > > Sheldon My 70-300 G has the plastic mount. It's holding up a lot better than I anticipated. >> I've noticed that some manufacturers are using a plastic lens mount on >> DSLR lenses. I realize this isn't a "normal" plastic, but how long [quoted text clipped - 6 lines] > My 70-300 G has the plastic mount. It's holding up a lot better than I > anticipated. I guess my point is that the quality of your lens mount is not something you should even have to think about. > I guess my point is that the quality of your lens mount is not > something you should even have to think about. True, and after having it hold up perfectly for a year, I don't think about it. |
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